This needs to come from a technical point of view, not your personal feelings. You also need to explain why you like/dislike the storyline in whatever FF you think is the best/worst. Lets see how we do.

Best FF story; Final Fantasy X
No FF is without its flaws, but Final Fantasy X did a good job at keeping those to a minimum whilst maintaining an engrossing story with believable characters that I think a lot of us could relate to. Religion was used in this game in the very way its used in the real world; to manipulate and control people. Its theme of religion being used as a tool for evil was so heavily entwined in this story that I would even say the enemy in this case was 'god' itself. Defeating 'sin' was the only way people could reach salvation, but sin was something created by yevon itself, and most certainly not a burden to be carried by the population. teaching them this only lead to the sacrifice of summoners at the end of their pilgramage. Becuase of this religion, it even lead Yuna's closest friends to accept her death for a 'greater good'. This is how I relate to Tidus's feelings. It seems only an outsider could give true insite to the doctrinated population of Spira, that what was happening was wrong and had to stop. His feelings of frustrations from being the only person who saw things differently and being singled out for his thoughts and feelings towards what everyone considered normal, is something you should all be able to relate to on some level. People refer to him as a wimp etc, but I think a lot of people miss the point. He was a wimp as a kid, and he grows throughout the duration of the story. He shows great character development and deals with so many issues along the way its mind boggling how people ignore that. In summary, Killing god(yu-yevon) and living without fear of 'sin', is a beautiful concept.


Worst FF story; Final Fantasy XIII series
What a mess... Ill just start with the characters being very one dimensional and shallow. No growth whatsoever. The story also manages to somehow be oversimplified and overcomplicated at the same time. I know they are opposing ideas, but you'd know what I mean if you played through a story about trying to save lightnings sister and then 'everything else' along the way. I cannot even describe this to you. Ill let someone else since I doubt im the only one that feels this way.